Dr. Murray Feingold: A rash with new-age roots

Tuesday

Jun 23, 2009 at 12:01 AMJun 23, 2009 at 10:15 PM

A 10-year-old boy was seen by his doctor because his mother noticed a red, very slightly raised, reticulated or lacy rash on the top of both of the child's thighs. Except for some itchiness he had no other symptoms. What could be the cause of this rash that had such a specific location?

Dr. Murray Feingold

A 10-year-old boy was seen by his doctor because his mother noticed a red, very slightly raised, reticulated or lacy rash on the top of both of the child's thighs. Except for some itchiness he had no other symptoms.

What could be the cause of this rash that had such a specific location?

Similar rashes may be due to a viral infection, but they are usually more generalized. The same is usually true for a drug-reaction rash.

A rash due to contact dermatitis may be located in specific areas. This type of rash occurs when the skin is in contact with an irritant or something that can cause an allergic reaction.

But this was not the cause of this child's rash.

The cause of the rash was due to something most of us use every day - a computer, in this case, a laptop computer. The youngster used the laptop for at least two hours each day and during this time, it was propped on his thighs.

A laptop computer emits infrared radiation and heat. Repeated exposure to increased heat can result in such a skin rash. The specific diagnosis of the rash is Erythema Ab Igne. I'm sure not many of you have ever heard of this condition, but it is not rare.

Small, slightly raised red lesions first appear where the laptop is located. The skin then forms a red, lacy appearance with areas of increased pigment. At times there maybe a burning sensation or some itching.

This condition also takes place when other sources of heat are placed on the skin such as a hot water bottle or heating pad.

It has been reported on the faces of cooks who work over an open fire. Or people who sit close to a fire in their homes.

The rash usually goes away when the area is no longer exposed to infrared radiation and heat.

Massachusetts-based Dr. Murray Feingold is the physician in chief of the National Birth Defects Center, medical editor of WBZ-TV and WBZ radio, and president of the Genesis Fund. The Genesis Fund is a nonprofit organization that funds the care of children born with birth defects, mental retardation and genetic diseases.

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